The studies presented here are designed to; (i) identify the molecular mech isms involved in gene regulation and hyperplasia caused in rats by beta-adrenergic recept (beta-AR) stimulation; (ii) examine the effect(s) of irradiation on beta-AR induced g e expression and salivary protein composition; (iii) understand the role of the extracel lar matrix components and their integrin receptors in rat parotid gland proliferation d differentiation during gland development; (iv) determine the different sign transduction pathways involved in the expression of c-fos, c-jun and jun B genes, in a s ivary cell line (A5). During this reporting period we have; (1) constructed cDNA libra es from parotid glands of isoproterenol treated rats and used sub- tractive hybridi tion for the identification of cDNA clones corresponding to specific mRNAs in the paroti glands of isoproterenol treated rats; (2) isolated the acidic PRP (PRP33) gene;(3) de nstrated that a single dose (15Gy) of ionizing radiation has no effect on beta-AR stimula on induced changes in PRP transcription rates and salivary composition; (3) shown that aminin B1, B2, collagen IV genes and alpha6 and beta1 integrin genes and beta1 protein are highly expressed during the early stages (1, 7 and 14) of parotid gland developmen and are present at basal levels at older ages (21, 42 and 90 days); and (4) identif d the intracellular signals involved in the differential expression of c-fos, c-j and jun B genes in A5 cells, after different stimuli.